Bull. Korean Math. Soc. 2020; 57(4): 973-990
Online first article May 7, 2020 Printed July 31, 2020
https://doi.org/10.4134/BKMS.b190666
Copyright © The Korean Mathematical Society.
Burcu Ungor
Ankara University
For the question ``when is $E(_RR)$ a flat left $R$-module for any ring $R$?", in this paper, we deal with a class of modules partaking in the hierarchy of injective and cotorsion modules, so-called Harmanci injective modules, which turn out by the motivation of relations among the concepts of injectivity, flatness and cotorsionness. We give some characterizations and properties of this class of modules. It is shown that the class of all Harmanci injective modules is enveloping, and forms a perfect cotorsion theory with the class of modules whose character modules are Matlis injective. For the objective we pursue, we characterize when the injective envelope of a ring as a module over itself is a flat module.
Keywords: Injective module, Matlis injective module, Harmanci injective module, cotorsion module, flat module, character module, envelope
MSC numbers: Primary 16D10, 16D40, 16D50, 16E30
2013; 50(2): 459-467
1999; 36(4): 693-699
2010; 47(4): 693-699
© 2022. The Korean Mathematical Society. Powered by INFOrang Co., Ltd